This invention relates generally to ring laser gyroscopes, and more specifically, to systems and methods for utilizing pulsed radio frequencies within ring laser gyroscopes.
At least some known ring laser gyroscopes (RLGs) utilize a direct current (D.C.) voltage discharge in order to start and maintain laser beams within a discharge cavity located in a block of the RLG. A discharge cavity is also sometimes referred to as a gain bore or discharge bore. In such a utilization, D.C. electrodes must be in direct contact with a gain medium of the laser that is contained within the discharge bore. In order to prevent external materials from leaking around these D.C. electrodes, an interfacial seal is used to bond the electrodes to the laser block. The integrity of such interfacial seals has historically limited the temperature range, reliability, and lifetime of RLGs which employ the interfacial seals.
Often the gain necessary to sustain the laser beams within an RLG require discharge currents which are powerful enough to sputter cathode material from the electrodes into the gain medium. This sputtering contaminates the gain medium which results in shortening the laser lifetime and hence gyro reliability and performance. Additionally, the cathode or cathodes, depending upon the RLG configuration, pump gases from the gain medium producing undesirable gas mix changes.
Other known ring laser gyroscopes employ capacitively coupled radio frequency (RF) energy which maintain the laser beams within the gyroscope through discharge of the RF energy. In such gyroscopes, electrodes transmitting RF energy are deposited onto an outer surface of the laser block. Still another known RLG employs an inductive coil wrapped around one leg of the discharge bore within the laser block. In this gyroscope embodiment, the inductive coil may be embedded within the laser block itself. As still another alternative, a capacitively coupled RF apparatus which includes two plates, is embedded within the laser block. When utilizing such an apparatus, one leg of the discharge bore is juxtaposed between two of the plates.
These RLGs couple continuous wave RF energy into the gain medium of a ring laser gyroscope thereby eliminating the need for electrodes within the discharge bores and the resulting problems associated with the sealing of the laser block. However, dynamic impedance characteristics of the gain medium within the discharge bore can cause problems related to controlling an amount of power delivered to the gain medium when utilizing such continuous wave (CW) RF signals.